1. Field of the Invention
The present invention relates to an exclusively vacuum-operated suction gripper for use in building machines. The invention can be used wherever, under restricted conditions of space, small articles are to be extracted from a machine and transported. More specifically, the present invention is a suction stroke cylinder.
2. Description of the Related Art
It is known to use vacuum-operated suction grippers to suction up and move small articles during production of various machines and the like. For this purpose, in addition to the suction elements, it is also necessary to have pressure elements to operate the feed movement or the stroke movement of the suction elements. As a result, the suction gripper sometimes becomes too large for many applications.
The object of the present invention is to provide a suction gripper that makes it possible to transport very small components in a very restricted space.
The suction gripper according to the present invention has a cylinder and a piston for executing a suction stroke having a first and a second stroke position. A cylinder housing with a cylinder space is provided, which, at one end, has an orifice to atmospheric pressure, against which the cylinder space is sealed off by means of the piston prestressed by a compression spring. A piston rod projects from the other end of the cylinder space for executing a stroke. The cylinder space has a constant connection to a vacuum duct via a first passage bore in the cylinder housing. The piston rod has a central bore, in the projecting end. The central bore can be connected in its interior to the vacuum duct via a radial bore in the piston rod and a second passage bore in the cylinder housing. At the projecting end of the piston rod, the central bore is closed by means of a suction or sucking element in order to suction a component. In the first stroke position, the piston bears against the orifice and the radial bore is closed by the cylinder housing, so that there is no connection to the vacuum duct. In the second stroke position, the piston is displaced by a vacuum being applied to the cylinder space, so that the radial bore is connected to the second passage bore and a vacuum is applied at the central bore.
In order to trigger the valve function between the stroke of the suction gripper and suctioning the component, the vacuum is applied to the central bore in the piston rod via a control edge at the second passage bore in the cylinder housing.
The advantage of this suction gripper is its small construction dimensions. These are obtained primarily because the same vacuum source is used both for the stroke and for suctioning the article to be moved. The two operations, in this case, are executed automatically in succession after only one switching signal.
In one embodiment of the suction gripper, the vacuum duct is located in the wall of the cylinder housing which is then connected to the vacuum source.
It is also possible, however, for the cylinder housing to be arranged in a transport device and for the vacuum duct to be located in this transport device.
If one or more components are to be moved by suction grippers in a manufacturing plant, in order to transport them to a further processing station, the suction gripper is brought into a position opposite the article to be suctioned and a switching signal is triggered. At the same time, a vacuum is introduced into the cylinder space via the vacuum duct. As a result of the pressure difference between the atmospheric pressure, the pressure on the outside of the piston and the relative or partial vacuum in the cylinder space, the piston is drawn towards the compression spring. The piston rod, together with the sucking element, is pressed onto the article to be moved. Shortly before the piston rod reaches the end of the stroke, a valve function comes into force. The radial bore reaches a control edge at the second passage bore in the cylinder housing and a vacuum is introduced into the central bore of the piston rod. The vacuum causes the sealing edge on the suction element to be applied firmly to the article to be moved. In this position, the article to be moved can be transported to another processing station. Here, the article is brought into the necessary position and the vacuum is switched off by means of a renewed switching signal. The pressure in the cylinder space rises and the piston rod slides back into the cylinder housing. The central bore in the piston rod is thereby separated from the vacuum and the suction element comes loose from the article to be moved. This operation can be accelerated if a brief blowing pulse is applied to the vacuum duct.
A suction gripper is thus provided, which can also be used for transporting small components in special machines and fixed-cycle lines. The essential advantages of the suction gripper according to the present invention arise from the small compact design, the application of only one form of energy and the supply of only one switching signal both for the stroke and for the sucking up.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.